Room and low temperature brewing with yeast immobilized on gluten pellets
ABSTRACT A biocatalyst prepared by the immobilization of a cryotolerant strain of Saccharomyces cerevisiae on gluten pellets was used for batch and continuous fermentation at low temperatures. The immobilized yeast showed important operational stability in repeated batch fermentations without a decrease of activity even at 0 and 5°C. Repeated batch fermentations using the biocatalyst resulted in improvement of ethanol productivity in comparison with bottom brewing fermentation and free cells using the same yeast strain. At 0 and 10°C, the fermentation rate was four and seven times higher than that of free cells, respectively. For immobilized yeast, diacetyl and polyphenol contents were lower and the alcohol concentration higher at low temperatures (0–7°C) when compared to free cells. Fine clarity was also observed in the beers. Continuous brewing using gluten-supported biocatalyst had an operational stability of 3 months with relatively high productivity and without contamination. Polyphenol and bitterness contents were lower in the continuous process than those of batch fermentations, but at low temperature (5°C) they were higher. The diacetyl content was higher than in batch fermentations and beers had a fine aroma and taste.
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ABSTRACT: The effects of temperature and inlet pH of the medium on the ethanol productivity and activity of the immobilized Z. mobilis cells during continuous fermentation of glucose have been studied at various temperatures and pH. On changing the temperature from one steady state level to a new one, 6-8 h were required in order to fully experience the effect of a change in temperature; whereas 8-20 h were required on changing the pH. The optimum temperature of 37 degrees C and a broad pH range of 4.4-6.0 were observed for maximum ethanol productivity and ethanol yield.Biotechnology and Bioengineering 07/1986; 28(6):824-8. · 3.65 Impact Factor
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ABSTRACT: Saccharomyces cerevisiae yeast immobilized in calcium alginate gel beads was employed in packed-bed column reactors for continuous ethanol production from glucose or cane molasses, and for beer fermentation from barley malt wort. With properly balanced nutrient content or periodical regeneration of cells by nutrient addition and aeration, ethanol production could be maintained for several months. About 7 percent (w/v) ethanol content could be easily maintained with cane molasses diluted to about 17.5 percent (w/v) of total reducing sugars at about 4 to 5 h residence time. Beer of up to 4.5 percent (wv) of ethanol could be produced from barley wort at about 2 h residence time without any addition of nutrients.Biotechnology Letters 12/1980; 3(1):21-26. · 1.85 Impact Factor
Article: Beer Brewing with Immobilized Yeast[show abstract] [hide abstract]
ABSTRACT: Beer was brewed continuously with Saccharomyces uvarum immobilized in calcium alginate gel beads. When wort fermented for a short period, and containing 8.5 mg/l of dissolved oxygen, was pumped into the bottom of a 2.5 l column reactor packed with immobilized yeast beads (54 percent of the total column volume) at a flow rate of 120 ml/h, 2.25 mg/l of total diacetyl was formed. However, when the wort contained 0.04 mg/l of dissolved oxygen, only 0.05 mg/l of total diacetyl was formed. Based on these results, a new fermentation system incorporating an immobilized yeast reactor was developed for the rapid production of beer of excellent quality containing a low level of diacetyl precursors.Nature Biotechnology 04/1985; 3(5):467-470. · 32.44 Impact Factor